The Butts fire broke out shortly after noon and quickly sped across dry, rugged terrain near Butts Canyon Road in the Pope Valley area of Napa County, the California Department of Forestry and Fire Protection said.

The agency said the blaze was about 30% contained Tuesday evening. Earlier in the day, walls of flame forced officials to evacuate homes in Berryessa Estates and along Butts Canyon Road, fire officials said.

About 100 firefighters worked amid 90-degree heat to cut containment lines and spray water on hot spots as the fire devoured parched brush and timber.

Crews on the ground were aided by an air attack that involved three helicopters and six fixed-wing tankers that were dropping fire retardant along the fire's flanks.

The blaze broke out as the National Weather Service was predicting above-normal temperatures for much of Northern California for the remainder of the week. The cause of the fire was under investigation.